This research proposal seeks to use an in vitro engineered model of the human oral mucosa to gain novel insights into HIV-1 oral transmission and on the consequences of HIV-1 infection on the biology of the oral mucosa. Epithelial cells and fibroblasts will be isolated from small pieces of palatal mucosa originating from gingival grafts and used to design an Engineered Human Oral Mucosa (EHOM). Lamina propria will be produced by mixing bovine skin Type I and Type III collagens with gingival fibroblasts, and will then be seeded with gingival epithelial cells. To produce a stratified epithelium, the EHOM will be cultured at the airliquid interface to allow organization of the epithelium into its different strata including the stratum corneum. This model constitutes a stable, reproducible and dynamic source of gingival tissue. The EHOM will be used to analyze the transfer of cell-free or cell-associated HIV-1 across the oral mucosa, and to decipher the specific role(s) of resident cells (i.e. epithelial cells and fibroblasts) and immunocompetent cells (i.e. dendritic cells, lymphocytes, macrophages) in this process. The tissue response to HIV-1 infection will be investigated in terms of structural integrity, keratin distribution, cytokines production, as well as secretion of beta-defensins and their influence on viral transmission. The use of EHOM model will also be an appropriate tool to study the responses of HIV-infected mucosal cells to opportunist pathogens such as Candida albicans. [unreadable] [unreadable]